Device and method for monitoring pain

Abstract

Devices and methods for monitoring pain in a subject, including a wearable device in communication with an analysis system that monitors pain in a subject using measurements of electrodermal activity in the subject are disclosed.

We claim the following: 
     
         1 . A device to monitor pain in a subject, the device comprising:
 a portable unit comprising:
 a galvanic skin response sensor comprising:
 at least two electrodes held in a fixed position on the skin of the subject; 
 at least one additional sensor; and 
 an impedance converter operatively connected to the at least two electrodes; 
 
 a microcontroller operatively connected to the impedance converter and to the at least one additional sensor wherein the microcontroller operates the impedance converter; and 
 a wireless transmitter operatively connected to the microcontroller; and 
   an analysis unit operatively connected to the portable unit, the analysis unit comprising:
 a wireless receiver; 
 a computing device operatively connected to the wireless receiver, the computing device comprising:
 at least one processor; 
 a computer readable media (CRM) encoded with a data analysis application executable on the at least one processor. 
 
   
     
     
         2 . The device of  claim 1 , further comprising at least one clip to hold the at least two electrodes held in a fixed position on the skin of the subject, wherein each clip of the at least one clips comprises a strip of a flexible material formed into a C-shape. 
     
     
         3 . The device of  claim 1 , wherein each electrode of the at least two electrodes is attached to an inner surface of the at least one clip. 
     
     
         4 . The device of  claim 2 , wherein the at least one clip fits over a hypothenar eminence of a hand of the subject. 
     
     
         5 . The device of  claim 1 , wherein the at least one additional sensor is selected from the group consisting of a temperature sensor, a humidity sensor, a pulse rate sensor, a motion sensor, and any combination thereof. 
     
     
         6 . The device of  claim 1 , wherein the at least one additional sensor monitors at least one additional state selected from the group consisting of a physiological state of the subject, a motion of the subject, and an ambient environmental condition. 
     
     
         7 . The device of  claim 1 , wherein the impedance converter obtains at least one electrode measurement from the skin of the subject and calculates at least one measured skin impedance for the subject using the at least one electrode measurement. 
     
     
         8 . The device of  claim 7 , wherein the wireless transmitter:
 receives a plurality of signals from the microcontroller encoding raw data comprising: the at least one electrode measurement; the at least one measured skin impedance, at least one additional sensor measurement from the skin impedance of the subject, and any combination thereof; and   transmits a plurality of wireless signals encoding the raw data to the wireless receiver.   
     
     
         9 . The device of  claim 8 , further comprising a local storage module operatively connected to the microcontroller to store at least a portion of the raw data. 
     
     
         10 . The device of  claim 8 , wherein the wireless receiver receives the plurality of wireless signals encoding the raw data from the wireless transmitter. 
     
     
         11 . The device of  claim 8 , wherein the data analysis application calculates a pain index using the raw data. 
     
     
         12 . The device of  claim 8 , wherein the data analysis application comprises a plurality of modules executable on the one or more processors, the plurality of modules comprising:
 a signal processing module to convert the series of raw impedances into a series of input impedances;   a data quality module to eliminate at least one artifact from the series of input impedances using a correction rule and the at least one additional series of at least one additional raw physiological state of the subject to produce a series of processed impedances;   a calibration module to convert the series of processed impedances into a series of pain indices; and   a GUI module to generate one or more forms used to receive inputs to the analysis system and to deliver output from the analysis system.   
     
     
         13 . The device of  claim 1 , wherein the wireless receiver operates on a Zigbee protocol. 
     
     
         14 . The device of  claim 1 , wherein the microcontroller is an ATmega microcontroller. 
     
     
         15 . A pain sensing system for estimating a pain index representative of a perceived pain in a subject, the system comprising:
 a portable unit comprising:
 a galvanic skin response sensor to monitor a skin impedance of the subject, the galvanic skin response sensor comprising;
 at least two electrodes maintained in a fixed position and separation distance on a portion of skin of the subject; 
 at least one additional sensor; and 
 an impedance converter to obtain a plurality of electrode measurements and analyze the plurality of electrode measurements to calculate at least one measured skin impedance value; 
 
   a wireless data transmitter to transmit the plurality of electrode measurements, the at least one measured skin impedance, and a second plurality of additional sensor measurements to an analysis system;   the analysis system comprising:
 a wireless data receiver to receive the plurality of electrode measurements, the at least one measured skin impedance, and a second plurality of additional sensor measurements; 
 at least one processor; 
 a CRM comprising a data analysis application comprising a plurality of modules executable on the at least one processor, wherein the data analysis application calculates a pain index using the plurality of electrode measurements, the at least one measured skin impedance, and the second plurality of additional sensor measurements. 
   
     
     
         16 . The system of  claim 15 , wherein the at least one additional sensor monitors at least one additional state selected from the group consisting of a physiological state of the subject, a motion of the subject, and an ambient environmental condition. 
     
     
         17 . The system of  claim 15 , wherein the plurality of modules comprise:
 a signal processing module to smooth and/or filter the plurality of electrode measurements, the at least one measured skin impedance, and a second plurality of additional sensor measurements;   a data quality module to eliminate at least one artifact from the at least one measured skin impedance using a correction rule and second plurality of additional sensor measurements to produce at least one processed impedances;   a calibration module to convert the at least one processed impedances into at least one pain index value; and   a GUI module to generate one or more forms used to receive inputs to the analysis system and to deliver output from the analysis system.   
     
     
         18 . A method to monitor pain in a subject, the method comprising:
 positioning a portable unit on a hand of a patient, the portable unit comprising:
 a galvanic skin response sensor comprising:
 at least two electrodes held in a fixed position on the skin of the subject; 
 at least one additional sensor; and 
 an impedance converter operatively connected to the at least two electrodes; 
 
 a microcontroller operatively connected to the impedance converter and to the at least one additional sensor wherein the microcontroller operates the impedance converter; and 
 a wireless transmitter operatively connected to the microcontroller; 
   obtaining at least one electrode measurement from the palm of the subject;   calculating at least one measured skin impedance for the subject using the at least one electrode measurement;   receiving a plurality of signals from the microcontroller encoding raw data comprising: the at least one electrode measurement; the at least one measured skin impedance, at least one additional sensor measurement from the skin impedance of the subject, and any combination thereof; and   transmitting a plurality of wireless signals encoding the raw data to the wireless receiver;   analyzing raw data using an analysis unit operatively connected to the portable unit, the analysis unit comprising:
 a wireless receiver; 
 a computing device operatively connected to the wireless receiver, the computing device comprising:
 at least one processor; 
 a computer readable media (CRM) encoded with a data analysis application executable on the at least one processor. 
 
   
     
     
         19 . The method of  claim 18 , further comprising monitoring at least one additional state using the at least one additional sensor selected from the group consisting of a physiological state of the subject, a motion of the subject, and an ambient environmental condition. 
     
     
         20 . The method of  claim 18 , wherein the CRM comprises a plurality of modules executable on the at least one processor, the plurality of modules comprising:
 a signal processing module to smooth and/or filter the plurality of electrode measurements, the at least one measured skin impedance, and a second plurality of additional sensor measurements;   a data quality module to eliminate at least one artifact from the at least one measured skin impedance using a correction rule and second plurality of additional sensor measurements to produce at least one processed impedances;   a calibration module to convert the at least one processed impedances into at least one pain index value; and   a GUI module to generate one or more forms used to receive inputs to the analysis system and to deliver output from the analysis system.